Radiative transfer and power control with fractal metamaterial and plasmonics

ABSTRACT

Systems according to the present disclosure provide one or more surfaces that function as heat or power radiating surfaces for which at least a portion of the radiating surface includes or is composed of “fractal cells” placed sufficiently closed close together to one another so that a surface (plasmonic) wave causes near replication of current present in one fractal cell in an adjacent fractal cell. A fractal of such a fractal cell can be of any suitable fractal shape and may have two or more iterations. The fractal cells may lie on a flat or curved sheet or layer and be composed in layers for wide bandwidth or multibandwidth transmission. The area of a surface and its number of fractals determines the gain relative to a single fractal cell. The boundary edges of the surface may be terminated resistively so as to not degrade the cell performance at the edges.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/043,781, filed Oct. 1, 2013, which claims the benefit of U.S.Provisional Patent Application No. 61/744,651 filed Oct. 1, 2012. Theentire contents of all of which applications are incorporated herein byreference.

BACKGROUND

Effective thermal management is a concern in many industries and forvarious types of consumer goods. For example, heat build-up in acomputer's central processing unit (CPU) can degrade the computer'sperformance just as heat build-up (or “heat soak”) in an automobile'sbrakes or engine can degrade the automobile's performance. Many machinesand devices have performance limits that are often defined by how wellheat developed during operation is managed. Such heat build-up is oftena byproduct of power transmission and use.

Some common thermal management techniques rely on convective heattransfer. Convective heat transfer, often referred to simply asconvection, is the transfer of heat from one place to another by themovement of fluids. Convection is usually the dominant form of heattransfer in liquids and gases. Convection can be “forced” by movement ofa fluid by means other than buoyancy forces (for example, a water pumpin an automobile engine). For machinery and electronic components,convective cooling is typically employed.

A heat pipe or heat pin is a heat-transfer device that combines theprinciples of both thermal conductivity and phase transition toefficiently manage the transfer of heat between two solid interfaces. Atthe hot interface of a heat pipe a liquid in contact with a thermallyconductive solid surface turns into a vapor by absorbing heat from thatsurface. The vapor then travels along the heat pipe to the coldinterface and condenses back into a liquid releasing the latent heat.The liquid then returns to the hot interface through either capillaryaction or gravity, and the cycle repeats. Consumer electronics such aspersonal computers often utilized heat pipes for cooling processingunits.

Since they rely on fluids as media to transport heat, such convectiveand heat-pipe cooling techniques can present issues relating tomanagement (e.g., containment and pumping) of the fluids, and may not beappropriate for some applications.

Thermoelectric cooling employs the Peltier effect to create a heat fluxbetween the junction of two different types of materials. The Peltiereffect is the presence of heating or cooling at an electrified junctionof two different conductors and is named for French physicist JeanCharles Athanase Peltier, who discovered it in 1834. When a current ismade to flow through a junction between two conductors A and B, heat maybe generated (or removed) at the junction. A Peltier cooler, heater, orthermoelectric heat pump is a solid-state active heat pump whichtransfers heat from one side of the device to the other, withconsumption of electrical energy, depending on the direction of thecurrent. Such an instrument is also called a Peltier device, Peltierheat pump, solid state refrigerator, or thermoelectric cooler (TEC).They can be used either for heating or for cooling (refrigeration)although in practice the main application is cooling. It can also beused as a temperature controller that either heats or cools*

Thermoelectric cooling is reliant on supplied electricity for thecooling effect and consequently may not be desirable for someapplications.

SUMMARY

The present disclosure is directed to systems and techniques thatprovide for desired transfer of radiation by using close packedarrangements of resonators having fractal shapes, i.e., “fractal cells.”Systems and techniques according to the present disclosure provide oneor more surfaces that act or function as heat or power radiatingsurfaces for which at least a portion of the radiating surface includesor is composed of “fractal cells” (small fractal shapes) (as antennas orresonators) placed sufficiently closed close together to one another(e.g., less than 1/20 wavelength) so that a surface (plasmonic) wavecauses near replication of current present in one fractal cell in anadjacent fractal cell. A fractal of such a fractal cell can be of anysuitable fractal shape and may have two or more iterations. The fractalcells may lie on a flat or curved sheet or layer and be composed inlayers for wide bandwidth or multibandwidth transmission. The area of asurface (e.g., sheet) and its number of fractals determines the gainrelative to a single fractal cell. As each cell is fed plasmoniclyrather than directly, ‘dead’ or covered or out of resonance cells do notalter the ability of the other cells to work. The boundary edges of thesurface may be terminated resistively so as to not degrade the cellperformance at the edges. These surfaces may be referred to as fractalplasmonic surfaces (FPS's) and can provide benefits for thermalmanagement and/or power delivery.

Such a fractal plasmonic surface (FPS) may be used to transferradiation, e.g., via evanescent wave transfer. In doing so such surfacescan be used to remove radiative power and/or heat from one location toanother, or divert it to another location. Such surfaces may be used toessentially diffuse power delivered to a part of the FPS and dissipateand or distribute it to other specific parts or globally. Heat forexample, may be dissipated in this way, or a power “hotspot” supplied orhit with localized power may have the power spread out or diverted toother desired locations, e.g., different areas of a related machine orstructure. In some embodiments, a FPS on a closed or curved surface mayact as a cloaking device to divert power (in a wavelength or frequencyof interest) from one side of the device to the other. In otherembodiments, a refrigeration or cooling effect may be induced bytransferring heat away from a FPS.

Exemplary embodiments of the present disclosure can provide techniques,including systems and/or methods, for cloaking objects at certainwavelengths/frequencies or over certain wavelength/frequency ranges(bands). Such techniques can provide an effective electromagnetic lensand/or lensing effect for certain wavelengths/frequencies or overcertain wavelength/frequency ranges (bands).

In some embodiments, the effects produced by such techniques can includecloaking or so-called invisibility of the object(s) at the notedwavelengths or bands. Representative frequencies of operation caninclude, but are not limited to, those over a range of 500 MHz to 1.3GHz, though others may of course be realized. Operation at otherfrequencies, including for example those of visible light, infrared,ultraviolet, and as well as microwave EM radiation, e.g., K, Ka,X-bands, etc. may be realized, e.g., by appropriate scaling ofdimensions and selection of shape of the resonator elements.

Exemplary embodiments of the present disclosure can include a novelarrangement of resonators in a lattice-like configuration. Thearrangements can include resonators of several different sizes and/orgeometries arranged so that each size or geometry (“grouping”)corresponds to a moderate or high quality factor, “Q,” (that is moderateor low bandwidth) response that resonates within a specific frequencyrange.

For exemplary embodiments, fractal resonators can be used for theresonators in such structures because of their control of passbands, andsmaller sizes compared to non-fractal based resonators. Their benefitarises from a size standpoint because they can be used to shrink theresonator(s), while control of passbands can reduce or eliminates issuesof harmonic pass-bands that would resonate at frequencies not desired.

Further embodiments of the present disclosure are directed to scattereror scattering structures. Additional embodiments of the presentdisclosure are directed to structures/techniques for activating and/ordeactivating cloaking structures. Further embodiments of the presentdisclosure are directed to wideband absorbers.

It should be understood that other embodiments of FPS systems andmethods according to the present disclosure will become readily apparentto those skilled in the art from the following detailed description,wherein exemplary embodiments are shown and described by way ofillustration. The systems and methods of the present disclosure arecapable of other and different embodiments, and details of such arecapable of modification in various other respects. Accordingly, thedrawings and detailed description are to be regarded as illustrative innature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the disclosure may be more fully understood from thefollowing description when read together with the accompanying drawings,which are to be regarded as illustrative in nature, and not as limiting.The drawings are not necessarily to scale, emphasis instead being placedon the principles of the disclosure. In the drawings:

FIG. 1 depicts a diagrammatic plan view of a fractal plasmonic surface(FPS), in accordance with exemplary embodiments of the presentdisclosure;

FIG. 2 depicts a diagrammatic plan view of a resonator cloaking systemutilizing a number of cylindrical shells, in accordance with exemplaryembodiments of the present disclosure; and

FIG. 3 depicts a diagrammatic plan view of a resonator cloaking systemutilizing a number of shells having an elliptical cross-section, inaccordance with an alternate embodiment of the present disclosure;

FIGS. 4A-4C depict an example of a FPS in three differentconfigurations.

FIG. 5 illustrates the robustness or anti-fragility presented by a FPSunder conditions where some fractal cells are damaged or otherwiseinoperative; and

FIG. 6 depicts an example of a FPS used to dissipate incident radiation.

While certain embodiments depicted in the drawings, one skilled in theart will appreciate that the embodiments depicted are illustrative andthat variations of those shown, as well as other embodiments describedherein, may be envisioned and practiced within the scope of the presentdisclosure.

DETAILED DESCRIPTION

Systems and techniques according to the present disclosure provide fordesired transfer of radiation by using close packed arrangements ofresonators having fractal shapes, i.e., “fractal cells.” Systems andtechniques according to the present disclosure provide one or moresurfaces that act or function as heat or power radiating surfaces forwhich at least a portion of the radiating surface includes or iscomposed of “fractal cells” (small fractal shapes) (as antennas orresonators) placed sufficiently close to one another (e.g., less than1/20 wavelength) so that a surface (plasmonic) wave causes nearreplication of current present in one fractal cell in an adjacentfractal cell. A fractal of such a fractal cell can be of any suitablefractal shape and may have two or more iterations. The fractal cells maylie on a flat or curved sheet or layer and be composed in layers forwide bandwidth or multibandwidth transmission. The area of a surface(e.g., sheet) and its number of fractals determines the gain relative toa single fractal cell. As each cell is fed plasmonicly rather thandirectly, “dead” or covered or out of resonance cells do not alter theability of the other cells to work. The boundary edges of the surfacemay be terminated resistively so as to not degrade the cell performanceat the edges. These surfaces may be referred to as fractal plasmonicsurfaces (FPS's).

Such a fractal plasmonic surface (FPS) may be used to transferradiation, e.g., via evanescent wave transfer. In doing so such surfacescan be used to remove radiative power and/or heat from one location toanother, or divert it to another location. Such surfaces may be used toessentially diffuse power delivered to a part of the FPS and dissipateand or distribute it to other specific parts or globally. Heat forexample, may be dissipated in this way, or a power “hotspot” supplied orhit with localized power may have the power spread out or diverted toother desired locations, e.g., different areas of a related machine orstructure. In some embodiments, a FPS on a closed or curved surface mayact as a cloaking device to divert power (in a wavelength or frequencyof interest) from one side of the device to the other. In otherembodiments, a refrigeration or cooling effect may be induced bytransferring heat away from a FPS.

In some embodiments, power control may also be achieved through widebandabsorption by placing a resistive sheet at the edge of the fractalcells, creating a layer adjacent to the cells. Impinging electromagneticradiation will be absorbed and not reflected or scattered. A FPS may beused to wirelessly couple a device for power transmission by placing thepower as electromagnetic radiation on the FPS and then physicallyplacing the (to be) powered device closely to the FPS. A FPS may alsowork even if some of the cells are damaged or missing as a variety ofpaths exist to convey the plasmonic transmission. A FPS may also be usedto diffuse power away from one location to another or dissipate it so asto decrease “hotspots.” Heating and cooling as a wideband speed of lightheat-like pipe may also be done with the FPS.

Exemplary embodiments of the present disclosure can provide techniques,including systems and/or methods, for cloaking objects at certainwavelengths/frequencies or over certain wavelength/frequency ranges(bands). Such techniques can provide an effective electromagnetic lensand/or lensing effect for certain wavelengths/frequencies or overcertain wavelength/frequency ranges (bands). In some embodiments, theeffects produced by such techniques can include cloaking or so-calledinvisibility of the object(s) at the noted wavelengths or bands.Representative frequencies of operation can include, but are not limitedto, those over a range of 500 MHz to 1.3 GHz, though others may ofcourse be realized. Operation at other frequencies, including forexample those of visible light, infrared, ultraviolet, and as well asmicrowave EM radiation, e.g., K, Ka, X-bands, etc. may be realized,e.g., by appropriate scaling of dimensions and selection of shape of theresonator elements.

Exemplary embodiments of the present disclosure can include a novelarrangement of resonators in a lattice-like configuration. Thearrangements can include resonators of several different sizes and/orgeometries arranged so that each size or geometry (“grouping”)corresponds to a moderate or high quality factor, “Q,” (that is moderateor low bandwidth) response that resonates within a specific frequencyrange.

For exemplary embodiments, fractal resonators can be used for theresonators in such structures because of their control of passbands, andsmaller sizes compared to non-fractal based resonators. Their benefitarises from a size standpoint because they can be used to shrink theresonator(s), while control of passbands can reduce or eliminates issuesof harmonic pass-bands that would resonate at frequencies not desired.

Further embodiments of the present disclosure are directed to scattereror scattering structures. Additional embodiments of the presentdisclosure are directed to structures/techniques for activating and/ordeactivating cloaking structures.

Related fractal technology is described in the following: (i) U.S.Provisional Patent Application No. 61/163,824, filed 26 Mar. 2009 andentitled “Cloaking Techniques”; (ii) U.S. Provisional Patent ApplicationNo., 61/163,837, filed 26 Mar. 2009 and entitled “Scatterer”; (iii) U.S.Provisional Patent Application No. 61/163,913, filed 27 Mar. 2009 andentitled “Cloaking Techniques”; and, (iv) U.S. Provisional PatentApplication No. 61/237,360, filed 27 Aug. 2009 and entitled “SwitchingSystem for Cloak On Command”; the entire contents of all of whichapplications are incorporated herein by reference.

For exemplary embodiments, fractal resonators can be used for theresonators because of their control of passbands, and smaller sizes. Amain benefit of such resonators arises from a size standpoint becausethey can be used to shrink the resonator(s), while control of pass-bandscan reduce/mitigate or eliminate issues of harmonic passbands that wouldresonate at frequencies not desired.

Exemplary embodiments of a resonator system for use at infrared (ornearby) frequencies can be built from belts or loops having fractalcells on one or both sides. These belts or loops can function to slipthe infrared (heat) energy around an object located within the belts, sothe object is effectively invisible and “see thru” at the infraredfrequencies. Belts, or shells, having similar closed-packed arrangementsfor operation at a first passband can be positioned within a wavelengthof one another, e.g., 1/10k, ⅛k, ¼k, ½k, etc.

In cloak embodiments, as described in further detail below, an observercan observe an original image or signal, without it being blocked by thecloaked object. Using no power, the fractal cloak having FPS canreplicate the original signal (that is, the signal before blocking) withgreat fidelity. Exemplary embodiments can function in the infraredregion (e.g., −700 nm to −1 mm, corresponding to −430 THz to −300 GHz),providing 3:1 bandwidth; operation within or near such can frequenciescan provide other bandwidths as well, such as 1:1 up to 2:1 and up toabout 3:1.

FIG. 1 depicts a radiative system 100 having a fractal plasmonic surface(FPS), in accordance with the present disclosure. The FPS 102 includes aclose packed arrangements of resonators having fractal shapes (e.g.,“fractal cells”) as denoted by 110 and 120. The FPS 102 may be part of alarger surface or area 104. The individual fractal cells are separatedfrom the adjacent fractal cells but are sufficiently close to oneanother (e.g., less than 1/20 wavelength) so that a surface (plasmonic)wave causes near replication of current present in one fractal cell inan adjacent fractal cell. While preferred fractal shapes are shown inFIG. 1 as being hexagonal or snowflake-like, any suitable fractal shape(e.g., deterministic) may be used and such a fractal may have two ormore iterations. The fractal cells may lie on a flat or curved sheet orlayer and be composed in layers for wide bandwidth or multibandwidthtransmission. Each layer holding a FPS can utilize fractal cells ofdifferent size and shape that those of another layer.

Examples of suitable fractal shapes (for use for shells and/or ascatting object) can include, but are not limited to, fractal shapesdescribed in one or more of the following patents, owned by the assigneeof the present disclosure, the entire contents of all of which areincorporated herein by reference: U.S. Pat. No. 6,452,553; U.S. Pat. No.6,104,349; U.S. Pat. No. 6,140,975; U.S. Pat. No. 7,145,513; U.S. Pat.No., 7,256,751; U.S. Pat. No. 6,127,977; U.S. Pat. No. 6,476,766; U.S.Pat. No. 7,019,695; U.S. Pat. No. 7,215,290; U.S. Pat. No. 6,445,352;U.S. Pat. No. 7,126,537; U.S. Pat. No.7,190,318; U.S. Pat. No.6,985,122; U.S. Pat. No. 7,345,642; and, U.S. Pat. No. 7,456,799.

Other suitable fractal shape for the resonant structures can include anyof the following: a Koch fractal, a Minkowski fractal, a Cantor fractal,a torn square fractal, a Mandelbrot, a Caley tree fractal, a monkey'sswing fractal, a Sierpinski gasket, and a Julia fractal, a contour setfractal, a Sierpinski triangle fractal, a Menger sponge fractal, adragon curve fractal, a space-filling curve fractal, a Koch curvefractal, an Lypanov fractal, and a Kleinian group fractal. Whileexemplary fractal shapes are shown in FIG. 1, the present disclosure isnot limited to such and any other suitable fractal shapes (includinggenerator motifs) may be used in accordance with the present disclosure.

The fractal cells 110 and 120 can be formed on the FPS 102 by anysuitable techniques. Such techniques can include additive and/orsubtractive techniques. Suitable lithography techniques may be used forsome embodiments. In exemplary embodiments, the fractal shapes of thefractal cells 110 and 120 can be conductive traces that are deposited onthe underlying surface, e.g., a suitable substrate. Any suitabledeposition techniques can be utilized. In other embodiments, the fractalcells 110 and 120 can be etched or engraved onto a surface. Any suitablemicromachining or nanomachining techniques may be used.

Exemplary embodiments of system 100 can utilize a material for asubstrate that has low-loss characteristics in the infrared region tofacilitate heat transfer by fractal cells disposed on, disposed in, orsupported by the substrate, e.g., on a supporting surface provided bythe substrate. Examples of suitable materials for such substrates caninclude, but are not limited to, the following: chalcogenide-glasses ingeneral; high-purity As-S, As-Se, Ge-As-Se glasses; and,Ge30AsioSe3oTe30 glass, and the like.

FIG. 2 depicts a diagrammatic plan view of a cloaking system 200 and RFtesting set up in accordance with exemplary embodiments of the presentdisclosure. As shown in FIG. 2, a number of concentric shells (or bands)202 are placed on a platform (parallel to the plane of the drawing). Theshells include a flexible substrate (e.g., polyimide with or withoutcomposite reinforcement) with conductive traces (e.g., copper, silver,etc.) in fractal shapes or outlines, each separate shape representing afractal cell (e.g., similar to cells 110 and 120 of FIG. 1). The shells202 surround an object to be cloaked (shown as 204 in FIG. 1). Atransmitting antenna 1 and a receiving antenna 2 are shown at differentsides of the system 200, for the purposes of illustration. The shells202 can be held in place by suitable radial supports 206.

The shells indicated in FIG. 2 are of two types, one set (A1-A4)configured for optimal operation over a first wavelength/frequencyrange, and another set (B1-B3) configured for optimal operation over asecond wavelength/frequency range. (The numbering of the shells is ofcourse arbitrary and can be reordered, e.g., reversed.)

For an exemplary embodiment of system 200, the outer set of shells(A1-A4, with A1 being the innermost and A4 the outmost) had a height ofabout 3 to 4 inches (e.g., 3.5 inches) and the inner set of shells had aheight of about 1 inch less (e.g., about 2.5 to 3 inches). The spacingbetween the shells with a larger fractal shape (A1-A4) was about 2.4 cmwhile the spacing between shells of smaller fractal generator shapes(B1-B3) was about 2.15 cm (along a radial direction). In a preferredembodiment, shell A4 was placed between shell B2 and B3 as shown. Theresonators formed on each shell by the fractal shapes can be configuredso as to be closely coupled (e.g., by capacitive and/or evanescent-wavecoupling) and function to propagate energy by a plasmonic wave.

It will be appreciated that while, two types of shells and a givennumber of shells per set are indicated in FIG. 2, the number of shelltypes and number of shells for each set can be selected as desired, andmay be optimized for different applications, e.g., wavelength/frequencybands, including the optical bands, i.e., infrared, visible, andultraviolet, as well as x-ray.

FIG. 3 depicts a diagrammatic plan view of a cloaking system (orelectrical resonator system) according to an alternate embodiment inwhich the individual shells have an elliptical cross section. As shownin FIG. 3, a system 300 for cloaking can include a number of concentricshells (or bands) 302. These shells can be held in place with respect toone another by suitable fixing means, e.g., they can be placed on aplatform (parallel to the plane of the drawing) and/or held with aframe. The shells 302 can include a flexible substrate (e.g., polyimidewith or without composite reinforcement) with a close-packed arrangementof electrically conductive material formed on the first surface. Asstated previously for FIG. 2, the closed-packed arrangement can includea number of self-similar electrical resonator shapes. The resonatorshapes can be made from conductive traces (e.g., copper, silver, gold,silver-based ink, etc.) having a desired shape, e.g., fractal shape,split-ring shape, and the like. The shells 302 can surround an object tobe cloaked, as indicated in FIG. 3.

As indicated in FIG. 3 (by dashed lines 1 and 2 and arrows), the variousshells themselves do not have to form closed surfaces. Rather, one ormore shells can form open surfaces. This can allow for preferentialcloaking of the object in one direction or over a given angle (solidangle). Moreover, while dashed lines 1 and 2 are shown intersectingshells B1-B3 and A1-A3 of system 300, one or more shells of each groupof shells (B1-B3 and A1-A3) can be closed while others are open.Additionally, it should be appreciated that the cross-sections shown foreach shell can represent closed geometric shapes, e.g., spherical andellipsoidal shells.

As indicated previously, each shell of a cloaking system (e.g., system300) include multiple resonators in one or multiple close-packedconfigurations. The resonators can be repeated patterns of conductivetraces. These conductive traces can be closed geometric shapes, e.g.,rings, loops, closed fractals, etc. The resonator(s) can be self similarto at least second iteration. The resonators can include split-ringshapes, for some embodiments. The resonant structures are not requiredto be closed shapes, however, and open shapes can be used for such.

In exemplary embodiments of shell 300, the closed loops can beconfigured as a fractals or fractal-based shapes, e.g., as depicted byfractal cells 110 and 120 in FIG. 1. The dimensions and type of afractal shape for a fractal cell can be the same for each shell type butcan vary between shell types. This variation (e.g., scaling of the samefractal shape) can afford increased bandwidth for the cloakingcharacteristics of the system. This can lead to periodicity of thefractal shapes of common shell types but aperiodicity between thefractal shapes of different shell types.

It will be appreciated that the resonant structures of the shells may beformed or made by any suitable techniques and with any suitablematerials. For example, semiconductors with desired doping levels anddopants may be used as conductive materials. Suitable metals or metalcontaining compounds may be used. Suitable techniques may be used toplace conductors on/in a shell, including, but no limited to, printingtechniques, photolithography techniques, etching techniques, and thelike.

It will also be appreciated that the shells may be made of any suitablematerial(s). Printed circuit board materials may be used. Flexiblecircuit board materials are preferred. Other material may, however, beused for the shells and the shells themselves can be made ofnon-continuous elements, e.g., a frame or framework. For example,various plastics may be used. In exemplary embodiments, the undelyingsurface or substrate on which a FPS is formed can have low loss withrespect to the type of radiation that the FPS is designed for, so as tofacilitate the intended heat and/or power transfer or dissipation.

Exemplary embodiments of the present disclosure can provide techniques,including systems and/or methods, for providing a radar cross section ofdifferent sizes than as would otherwise be dictated by the physicalgeometry of an object. Such techniques (objects/methods) can be usefulfor implementations such as radar decoys where a given object (decoy) ismade to appear in radar cross section as like another object (e.g.,missile). Representative frequencies of operation can include those overa range of 500 MHz to 1.3 GHz, though others may of course be realized.Other frequencies, include those of visible light may be realized, e.g.,by appropriate scaling of dimensions and selection of shape of fractalelements.

FIGS. 4A-4C depict an example of a FPS 400 in three differentconfigurations. In FIG. 4A, the FPS 400A is shown physically coupledbetween two objects, a hot object and a colder object. Heat, in the formof radiative infrared energy, flows from the hot object to the colderobject via plasmonic coupling between fractal cells 402 of the FPS 400A.

FIG. 4B, a configuration of FPS 400B is shown having resistive ends 404in addition to the fractal cells 402. The resistive ends 404 may be madeof any suitable resistive material and my any suitable techniques. Suchresistive ends may be useful for power dissipation in some applications.FIG. 4C shows another embodiment of FPS 400C that has a resistive layeror edge 406 instead of the resistive ends 404 shown previously (thoughboth such resistive elements may be used for a single FPS).

FIG. 5 illustrates the robustness or anti-fragility presented by a FPS500 under conditions where some fractal cells are damaged or otherwiseinoperative. As shown, FPS 500 has a close-packed arrangement of fractalcells, indicated by circles 502. The close-packed arrangement providesmany paths by which energy may be transferred from one area of the FPSto another, even in the presence of damaged or otherwise inoperativefractal cells (represented by the black squares shown).

FIG. 6 depicts an example of a FPS 600 used to dissipate incidentradiation, which may be directed radiation of high intensity or fluence.As shown, radiation that is incident on a localized area of the FPS 600is dissipated (indicated by concentric rings) across the surface of theFPS 600 via plasmonic coupling and radiative transfer between thefractal cells 602 of the FPS 600.

While embodiments are shown and described herein as having shells in theshape of concentric rings (circular cylinders), shells can take othershapes in other embodiments. For example, one or more shells could havea generally spherical shape (with minor deviations for structuralsupport). In an exemplary embodiment, the shells could form a nestedarrangement of such spherical shapes, around an object to be shielded(at the targeted/selected frequencies/wavelengths). Shell cross-sectionsof angular shapes, e.g., triangular, hexagonal, while not preferred, maybe used.

One skilled in the art will appreciate that embodiments and/or portionsof embodiments of the present disclosure can be implemented in/withcomputer-readable storage media (e.g., hardware, software, firmware, orany combinations of such), and can be distributed and/or practiced overone or more networks. Steps or operations (or portions of such) asdescribed herein, including processing functions to derive, learn, orcalculate formula and/or mathematical models utilized and/or produced bythe embodiments of the present disclosure, can be processed by one ormore suitable processors, e.g., central processing units (“CPUs)implementing suitable code/instructions in any suitable language(machine dependent on machine independent).

While certain embodiments and/or aspects have been described herein, itwill be understood by one skilled in the art that the methods, systems,and apparatus of the present disclosure may be embodied in otherspecific forms without departing from the spirit thereof

For example, while certain wavelengths/frequencies of operation havebeen described, these are merely representative and otherwavelength/frequencies may be utilized or achieved within the scope ofthe present disclosure.

Furthermore, while certain preferred fractal generator shapes have beendescribed others may be used within the scope of the present disclosure.Accordingly, the embodiments described herein are to be considered inall respects as illustrative of the present disclosure and notrestrictive.

What is claimed is:
 1. An electrical resonator system, comprising: aplurality of concentric electrical resonator shells, each shellincluding a substrate having first and second surfaces and aclose-packed arrangement of electrically conductive material formed onthe first surface, wherein the closed-packed arrangement comprises aplurality of self-similar electrical resonator shapes and is configuredto operate at a desired passband of electromagnetic radiation; andwherein the close-packed arrangements of at least two antenna shells aredifferent in size and/or shape; wherein the electrical system isconfigured and arranged so that radiation incident on the system from agiven direction has an intensity on a point-by-point basis such at eachrespective antipodal point, relative to an object placed at the centerof the system, the radiation has the same or similar intensity; andwherein the antenna system is configured and arranged so that radiationincident on the system from a direction in cylindrical coordinates hasthe same or similar intensity at the antipodal point after havingtraversed the antenna system.
 2. The system of claim 1, wherein saidpassband is about 2:1.
 3. The system of claim 2, wherein said passbandis about 3:1.
 4. A fractal based scatterer comprising: a shell composedof flexible substrate in the shape of a band joined in a cylindricalshape having a conductive coating with self-similar-shaped cutouts,wherein the scatterer produces a greater radar cross section for itsphysical size than would otherwise be produced by its physical sizealone.
 5. The scatterer of claim 4, wherein the substrate is polyimide.6. The scatter of claim 4, wherein the scatter is operational over arange of about 500 MHz to about 1.3 GHz.
 7. The scatter of claim 4,wherein the scatter provides a dynamic range of about less than 10 toabout more than 4.